1. Technical Field
The present invention relates to a liquid ejection head and a liquid ejection apparatus which eject liquid, in particular, relates to an ink jet recording head and an ink jet recording apparatus which discharge ink as liquid.
2. Related Art
An ink jet recording head as a representative example of a liquid ejection head is generally configured as follows. That is, the ink jet recording head is generally configured such that ink is supplied to a pressure generation chamber of a head main body through an ink flow path (liquid flow path) from an ink cartridge (liquid storage unit) which is filled with ink. Further, pressure is applied into the pressure generation chamber by a pressure generation unit such as a piezoelectric element so that ink droplets are ejected through a nozzle communicating with the pressure generation chamber.
For example, there is an ink jet recording head having the following configuration as a specific configuration of the ink jet recording head (for example, see JP-A-2003-11383). The ink jet recording head includes head main bodies, a head case to which the plurality of head main bodies are secured, and a cartridge case to which the head case is secured. Further, a circuit substrate which supplies a signal for driving a piezoelectric element is secured between the head case and the cartridge case.
The circuit substrate is held in a flow path member constituted by the head case and the cartridge case. However, most of an outer wall of the flow path member is constituted by an outer wall of the cartridge case. Therefore, if the flow path member is elongated because the flow path member needs to hold the plurality of head main bodies, the outer wall is easily deformed if the outer wall has rigidity which is equivalent to that of an outer wall when the flow path member is small. A space is generated on a joint between the head case and the cartridge case with the deformation. This raises a problem in that liquid enters an inner portion of the flow path member through the space. In particular, when the circuit substrate is provided therein, an electronic part is damaged and a wiring is short-circuited due to the liquid which has entered there. Further, even when the circuit substrate is not held in the flow path member, if liquid enters the inner portion of the flow path member, there arises a problem in that the liquid which has entered there may drop at an unexpected timing and contaminate a recording medium.
Further, if a thickness of the outer wall is increased for solving the above problems, the ink jet recording head is increased in size in addition to an increase in cost and molding failure is easily caused, resulting in a problem in that the ink jet recording head cannot be manufactured with inexpensive molding.
It is to be noted that the above problem arises not only in the ink jet recording head but also in a liquid ejection head which ejects liquid other than ink.